ATLANTA — After making it through last night's game at Class A Potomac with no problems, Ryan Zimmerman is set to come off the disabled list and rejoin the Nationals lineup tomorrow night in Pittsburgh.

Zimmerman, out since April 18 with a strained left hamstring, went 0-for-3 and reached on an error while on rehab at Potomac, playing six innings in the field without reporting any problems.

It was Zimmerman's only appearance on the rehab assignment — he was scratched from the lineup Tuesday night due to wet grounds at Pfitzner Stadium — but the Nationals aren't concerned he needs more at-bats before returning to the big leagues.

"I'm not concerned about him even playing," manager Davey Johnson said. "I think last year he did a stint on the DL, and he didn't rehab anywhere. I feel the same way this year."

Zimmerman is scheduled to work out on his own today at Nationals Park, then fly to Pittsburgh, where he'll meet his teammates after their charter flight arrives from Atlanta following tonight's series finale against the Braves. He'll be in the lineup tomorrow night against the Pirates, hoping to inject some life into a Nationals offense that currently ranks 28th in baseball with a .230 team batting average and .676 OPS.

Zimmerman's return will send top prospect Anthony Rendon back to Class AA Harrisburg. Rendon has played in seven games so far for the Nationals and has struggled at the plate, hitting .182 (4-for-22) with one RBI, four walks and seven strikeouts.